Azonitrile compounds are particularly useful as catalysts in certain polymerization processes such as, for example, the emulsion, dispersion solution and bulk polymerization of vinyl chloride. However, the azonitrile compounds which are thus employed must have a certain minimum purity. U.S. Pat. No. 3,783,148 issued to Julius Fuchs on Jan. 1, 1974 describes a process for preparing azonitriles by coupling aminonitriles in the presence of a hypochlorite. While such a production method yields azonitriles which are eminently suitable for most uses, the azonitriles thus prepared are not sufficiently pure for use in some polyvinyl chloride polymerization processes.